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Markbass SD800 Died

#6
skidmarkbass said:
My Markbass SD800 is unusable at the moment it has been cutting out. I'm out of warranty and I don't know if its worth fixing. Anyway, the other night I rigged up a QSC 1850 power amp with a Boss gt6b as a preamp and it really sounds quite good with my pbass. I might just use it instead of buying a new head.
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Step 1: Open the amp up and see if there are any visual clues. (Smell of smoke, or burned areas, or whatever.) See if any screws or plugs have come loose.
 
#8
skidmarkbass said:
No burned smell... I found a local guy that fixes amps and will evaluate it FREE. If the estimate isn't too bad I might have it fixed. My experience has been that amps are never the same after a major repair and I never trust them without having a backup.
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It won't be that hard to get fixed in the land of rocket science.
Might just need rebasing, even transistor amps can drift, bias wise.
Put them straight and they will continue without drifting much further,
as they must be well burned in now.:bassist:
 
#9
skidmarkbass said:
No burned smell... I found a local guy that fixes amps and will evaluate it FREE. If the estimate isn't too bad I might have it fixed. My experience has been that amps are never the same after a major repair and I never trust them without having a backup.
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I'd be careful there. Many 'local' guys who are not in Markbass's US service network probably would not have much of a clue as to what is needed (although probably a good first step if it won't cost you anything to see if it is just a jack or something).

Markbass's US service network is getting pretty good reviews from the very few owners who have issues with these VERY reliable heads. Even if you need to replace the board, the price is not particularly high at this point.

Contact Peter Murray through PM and he will help you sort it out.
 
#10
KJung said:
I'd be careful there. Many 'local' guys who are not in Markbass's US service network probably would not have much of a clue as to what is needed (although probably a good first step if it won't cost you anything to see if it is just a jack or something).

Markbass's US service network is getting pretty good reviews from the very few owners who have issues with these VERY reliable heads. Even if you need to replace the board, the price is not particularly high at this point.

Contact Peter Murray through PM and he will help you sort it out.
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Note that Peter is no longer the rep, but he can tell you who to contact. He's still on TB and says he's willing to do as much, and probably more.
 
#14
Tried SD800 again at home to replicate the problem, and at home the amp DOES NOT cut out. I played for an hour with no problem. Now I'm starting to think it could have been the electricty at the rehersal studio. I'm going to bring an extension cord next time and try a different outlet. I also did notice that the gator hard case that I use for the head does not have a side openning. The MB fan is on the side not the back, maybe the amp gets too hot. When i tested it at home it was not in the hard case.
 
#15
skidmarkbass said:
Tried SD800 again at home to replicate the problem, and at home the amp DOES NOT cut out. I played for an hour with no problem. Now I'm starting to think it could have been the electricty at the rehersal studio. I'm going to bring an extension cord next time and try a different outlet. I also did notice that the gator hard case that I use for the head does not have a side openning. The MB fan is on the side not the back, maybe the amp gets too hot. When i tested it at home it was not in the hard case.
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It could be that the protection circuit was just doing its' job. Maybe the heat Or Maybe crappy Electric supply like you said. I am seriously considering a top quality power conditioner because of problems like these with My Class D Amp. You could always bring a test meter with you to next rehearsal and check for Voltage Drop and look for 60HZ Frequency. There may be other things to check but I don't know what they are. I just know that certain class D amps don't like Crappy Power supplies. I have had 2 amps fry on me so far from the same Outlet at my drummers house. I am bringing my Meter with me next time we Jam to test the Outlet in question.
 
#18
The SD800 is definitely worth repairing - IF there is a problem at all.

Sometimes, it is only the protection device that is getting hinky - it happens.

Note that most power conditioners are just filters and don't do anything about low voltage. It takes a pretty large unit to have that ability. Such devices usually have a giant multi-tapped transformer inside to adjust the voltage up or down.
 

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